1. Field of the Invention
The present invention relates to a method for connecting a low speed main shaft of a wind turbine to an input shaft of a transmission gearbox of the wind turbine.
2. Description of the Related Art
The purpose of such a connection between the main shaft and the input shaft of a transmission gearbox is to transmit torque from the main shaft which is connected to the rotor hub of the wind turbine and which is driven usually at a slow speed by the action of the wind on the rotor blades to an input shaft of the transmission gearbox.
Hereby, the slow rotation of the input shaft is transformed in the transmission gearbox into a fast rotation at the output shaft of the transmission gearbox, which output shaft is normally driving an electric power generator.
According to the present state of the art a lot of different methods for connecting a main shaft of a wind turbine to an input shaft of a transmission gearbox are known.
The present invention however is limited to the types of methods of connecting whereby the transfer of torque through the connection is realized based on the principles of friction between materials.
In recent developments there is a tendency to design wind turbines of multi megawatts, for instance 3 MW, having growing dimensions.
In order to cope with the loads on such wind turbines with big dimensions, a lot of effort is put in integrating the different components of the wind turbine in order to reduce the weight and size of the wind turbine.
In particular in new designs the whole drive train is of a more and more integrated type.
Growing dimensions combined with more integrated designs make the transmission of torque from the main shaft to the input shaft problematic.
Indeed, the bigger the dimensions of the wind turbine, the higher the torque to be transmitted, whereby on the other hand the limited dimensions of the integrated designs, in particular the limitations on the diameter used for the connection between the low speed main shaft and the input shaft of the gear box, also limit the maximum torque that can be transmitted.
This is in particular a disadvantage of the existing drive trains using a connection between main shaft and input shaft of the gear box based on the principles of friction.
The present invention aims at a method for connecting the low speed main shaft of a wind turbine to an input shaft of a gearbox of that wind turbine, which does not show one or more of the above and other disadvantages.